Description: The CH-46 Sea Knight was developed by Boeing to meet the US Marine Corps (USMC) requirements for a medium-lift helicopter as a replacement for the UH-34. In 1964 Boeing delivered the first two three-blade rotor CH-46A aircraft powered by two T58-GE-8 engines rated at 1,250-shp each. In 1968 H-46 production model was the CH-46D which was powered by two more powerful T58-GE-10 engines rated at 1,400-shp each. In 1978 the USMC took delivery of the first CH-46E Sea Knight aircraft which was the result of upgrading existing D models to the new standard. The CH-46E Sea Knight was powered by two T58-GE-16 engines rated at 1,870-shp each. Currently, CH-46E is the only H-46 model operated by the USMC. The US Navy also ordered the H-46 aircraft under the UH-46 designation. The USMC CH-46A and CH-46D models were delivered to the US Navy as the UH-46A and UH-46D.

The US Navy's H-46 helicopter primary mission is shipboard delivery of personnel and cargo. The USMC CH-46E Sea Knight provides all-weather, day/night assault transport of combat troops operating from the US Navy's carriers, amphibious ships and landing docks anywhere in the world. Transport of supplies and equipment is a secondary task for the USMC. H-46 is flexible enough to conduct additional missions such as search and rescue, medical evacuation, etc.

In the late 1980s the USMC CH-46E fleet was retrofitted with the Safety, Reliability and Maintainability modification kit provided by Boeing. In the 1990s the USMC also ordered additional modifications applied to the engines, flotation system, etc aimed at extending the aircraft's service life well into the 21st century. As of December 2005, the USMC has firms commitments to procure 360 MV-22 tilt-rotor aircraft as a replacement for the CH-46E helicopter.